Method and apparatus for severing casings and the like



Dec. 24,1963 J. G. JACKSON 4 METHOD AND APPARATUS FOR SEVERING CASINGS AND THE LIKE Filed Jan. 4, 1960 INVENTOR. JOH/V GORDON JACKSON AITORNEY United States Patent Office 3,1 l5,l8d Patented Dec. 24, 1963 3,115,184 METHGD AND APPARATUS F012 SEVERE-LNG CASKNGS AND TEE LHKE John Gordon Jackson, Denver, Colo., assignor to Well Completions, Incorporated, Denver, Colo, a corporation of Colorado Filed Jan. 4, 1960, Ser. No. 491 12 Claims. (Ci. 166-35) This invention relates to a novel and improved method and apparatus for severing objects in a well bore, such as a well casing and the like.

Whenever objects are to be retrieved from a well bore, such as for example a drill stem, casing, bit or other material, it is customary to employ some heat generating substance at a predetermined location in the well bore which through various means may be ignited to develop a highly concentrated region of heat which is effective to cause destruction of the object at the desired point of removal either by melting or weakening followed by removal above the point of severance from the well bore. In accordance with the present invention, it is proposed to provide a greatly simplified yet reliable method and apparatus for starting and heating the object to an elevated temperature range above the temperature of combustion of a high temperature, heat generating substance which is delivered to the Zone of severance to cause the generation of even more intense heat and to such an extent as to convert the object to be removed to a molten and at least a partially vaporized state, and followed by the effective removal of the material severed from the well and of course the object itself.

It is accordingly a principal object of the present invention to proivde for an improved apparatus for severing objects lodged in a well bore which overcomes many of the shortcomings and disadvantages of the prior art by establishing a positive and complete way of causing ignition of a heat generating substance at the desired location of severance together with the rapid and effective removal of the severed material and object from the well bore.

It is another object to provide for a way of severing and removing an object such as a casing and the like from a well bore which enables use for the most part of equipment commonly used in the drilling of wells and which is further greatly simplified and more efficient in operation.

It is a further object to severe a casing and the like for removal from a well in which the casing is initially heated and maintained at an elevated temperature level at the desired location of severance, and above the temperature necessary for combustion of a high heat generating material, wherein the latter material is delivered to the location of severance to supplement the preliminary heating and rapidly develop heat of high intensity sufficient to cause melting and vaporization of the casing at the selected point of severance and thereby enable rapid severance and removal of the casing from the well.

It is a further object to provide for a method and means for frictionally engaging a substance positioned at the desired point of severance of an object in a well bore in such a way that the development of friction is sufiicient to cause the generation of heat above the temperature of combustion of the substance; and moreover, where the method and means employed in the development of friction is further adaptable for use in removing the severed material from the well bore.

It is an additional object to produce a working tool adapted to be suspended in a well bore to burn a combustible substance positioned at the desired location of severance of an object in the well bore, to deliver a high temperature heat generating gaseous medium into direct contact with the combustible substance whereupon the heat generated is suihcient to convert the object at an accurately defined area to a molten and at least a partially vaporized state, and where the force of delivery and return flow of the gas is effective to remove the molten and gaseous material from the well.

The above and other objects and advantages of the present invention will become more apparent from the following detailed description taken together with the accompanying drawings, in which:

FIGURE 1 is a cross sectional view illustrating the application of a preferred form of the present invention in the removal of a casing string from a well bore; and

FIGURE 2 is a section view taken on line 22 of FIGURE 1.

Referring more particularly to the drawings, the present invention will be described more in detail by reference to its application in the removal of a portion of a casing string C which, as shown in FIGURE 1, is positioned in a well bore B. However, it will become evident from the foregoing description that the present invention is adaptable for the purpose of removing various metal objects usually composed of iron or iron-base alloys which have become lodged or stuck in a well bore and is of course not limited to the severance of casing alone.

The apparatus employed in severing the casing at the desired location is generally indicated by reference numeral It? and will be seen to include an exothermic or suitable combustible substance 12 which may be positioned at the desired level in the casing by any desired expedient, such as for example, by first positioning a cementitious or similar layer 14 in the casing below the intended location of the substance 12. In addition, the apparatus broadly includes a rotary tool 16 which as shown may be connected to the lower end of a drill stem D for lowering through the casing into direct contact with the starter material 12.

Primarily on account of the unique method and apparatus employed, the combustible substance 12 may be composed of any one of a number of commercially available materials, and in this connection it is to be understood at the outset that the composition of the substance 12 together with its configuration and manner of disposition in the well bore forms no part of the present invention. For example, the substance employed may be any suitable solid, carbonaceous, coke or coal material having a relatively low kindling temperature which is capable of generating heat when ignited sufi'icient to raise the temperature of the metallic casing to an intermediate range on the order of 1000 F. or greater. In this connection, it is actually preferred to employ a substance which will bring the temperature of the metallic casing at an accurately defined area of severance up to a level above that required to ignite a combustible gas-air mixture which is circulated through the well in a manner to be described to develop a level of heat sufiicient to convert the casing to a molten and even a partially gaseous state. The combustible gas which may be used in the gas-air mixture is one conventionally used in the art for this purpose such as propane or butane or mixtures thereof.

In order to ignite the substance 12; and to provide for the intense and complete burning thereof at an elevated temperature, it is proposed to start the substance through the application principally of friction to an exposed portion thereof and to complement its burning through the delivery of a circulating medium composed preferably of a mixture of air and combustible gas. To this end, a rotary tool 16 is provided which may be secured by means of a collar 17 to the lower end of the drill stem D and which is dimensioned for lowering into the well into direct contact with the substance disposed Within or in contiguous relation to the object to be removed, such as the casing C. The rotary tool 16 preferably takes the form of an elongate hollow cylindrical member which is threaded at its upper end for connection to the drill collar 17 and which is rounded at its lower end into the form of a nose portion 18 with generally circular downwardly directed openings 19 extending through the lower rounded end 18. As shown in FIGURE 2, the openings 19 may may be spaced at suitable intervals throughout the lower end of the rotary tool and as will become apparent any desired number of openings may be employed and at any desired intervals. Although not shown the circulating medium is passed downwardly through the drill stem and rotary tool for ejection under pressure through the openings 19 so as to strike the top exposed surface of the substance 12. In addition, the rotary tool may be rotated in a well known manner by the drill pipe and also forced simultaneously downwardly into firm contact with the exposed surface of the starter substance to thereby effectively establish the combined application of the air-gas mixture and frictional contact with the substance 12. Through this expedient, an intense amount of heat is developed since the circulating medium will aid in the development of heat in striking the exposed surface of the material at a high velocity accompanied by the friction developed by rotation of the lower end of the rotary tool at the same point. In this connection, due to the amount of heat developed, it is preferable to either form or line the rotary tool with a refractory or ceramic material which is capable of withstanding the high temperatures developed once the materials are ignited and of course the constant circulation of the air-gas mixture will serve to cool the surface of the tool in passing therethrough. It is to be further noted that through the application of the gas and air, to initiate burning of the casing, that the increased availability of oxygen in the region of burning and especially in the confined region of a well bore will greatly intensify the heat generation thereof and enable very high temperatures of burning to be reached and in addition to establish rapid complete burning of the material. Moreover, the presence of the substance 12 in direct physical contact with the casing will initially heat the casing at an accurately defined location to an intermediate level to be supplemented by the gas at the same area and rapidly develop the necessary amount of heat to cause the metal to become converted to a molten or gaseous state. Of course the tool of the present invention is also adapted for use in burning a substance which in itself is sufficient to raise the temperature of the casing to a level into at least the molten range without the use of an auxiliary high tempertaure heat generating medium such as gas. However, air or oxygen should be directed through the tool to enable combustion of the substance.

Thus, as burning of the combustible material 12 progresses, the amount of heat generated will be such as to ultimately raise the temperature of the surrounding casing to its molten, and in many cases, its gaseous state, dependent upon the properties of the metal, such that at a localized region the casing will be completely destroyed and severed from the lower end of the casing set in the well bore. Thereafter, once the portion of the casing at the location of severance is destroyed, any gases formed will of course mix with the circulating medium being ejected through the rotary tool for return back to the surface of the Well.

From the above, it will be seen that there is provided a greatly simplified and reliable method for causing ignition of a starter material which in turn is the source of combustion for a gas-air mixture at the desired point of severance or destruction of an object, for example, which has become lodged or stuck in a well. This method consists essentially of positioning the starter substance 12 at .a location at or next to the desired area of severance followed by ignition of the substance, preferably through the utilization of a rotating member contacting its exposed surface; then by the circulation of a gas-air mixture under pressure the starter substance provides a constant source of combustion of the gas thereby to cause burning and eventual destruction of the object at that point. As mentioned, through the application of a gas and air under pressure in the presence of the substance 12 complete burning of the material is hastened together with the carrying off of any waste materials either from the severed casing portion or fuel itself.

Of course, various forms of apparatus may be employed to practice the present invention and for example the means to establish rotating frictional engagement with the starter material may take the form of other similar types of oscil ating or reciprocating instrument which may be held in firm frictional engagement with the material. In addition the circulating medium may either be injected through a hollow member forming the tool for frictionally engaging the material 12 or for example may be directed downwardly at the point of frictional engagement through a separate tubing lowered through the Well, and with the rotary tool being in the form of either a solid or hollow rodlike member. Moreover, to carry out the method of this invention various means of ignition may be employed as substitutes for the rotating frictional tool, such as, electrical or percussion types of igniters now commercially available and from this, the starter material provides a constant positive source of combustion to burn the gas as it moves into the elevated temperature region at the desired location in the well.

It will be accordingly understood that various modifications may be made in the method and means employed to carry out the present invention, especially in the composition of materials utilized without departing from the scope thereof, as defined by the appended claims.

What is claimed is:

l. A method of severing a casing and the like in a well bore comprising the steps of positioning a carbonaceous material in direct physical contact with the desired location of severance of the casing, burning an exposed portion of the material while directing an air-gas mixture against the exposed portion of the material to cause complete burning both of the material and the air-gas mixture, and continuously circulating the gas-air mixture through the casing to cause destruction of the casing and subseuent removal of the waste material accumulated during burning of the substance and easing said air-gas mixture being a mixture of a combustible gas and SllfilClEl'll', air to support its combustion and being capable of providing suflficient heat upon combustion of the gas to sever said casing.

2. A method of severing casings and the like according to claim 1 including the added steps of positioning a rotary member into frictional engagement with the carbonaceous material and rotating the member to cause burning of the material as the air-gas mixture is directed against the exposed portion of the material.

3. A method for severing objects in a well bore comprising the steps of positioning a heat generating combustible substance at the desired location of severance of the object, suspending a rotatable member in the well bore in direct contact with the combustible substance, rotating the member in frictional engagement with the combustible substance, simultaneously delivering to the well bore a high temperature heat generating gaseous medium into contact with the combustible substance, the temperature of ignition of the gaseous medium being below the temperature of combustion of the combustible substance, and the generation of heat from burning of the gaseous medium and combustible substance being at a temperature level and intensity to heat the object at the location of severance to at least the molten state,

4. A method for severing objects in a well bore comprising the steps of positioning a heat generating combustible material at the desired location of severance of the object in the well bore, positioning a generally tubular member in the Well bore with its lower extremity in frictional contact with the combustible substance, rotating the tubular member to cause burning of the combustible substance and simultaneously circulating an air-gas mixture through the tubular member, the temperature of combustion of the air-gas mixture being below the temperature of combustion of the combustible substance whereupon the combustible substance provides a constant source of combustion for the airgas mixture to bring about burning at a temperature sufficient to cause destruction of the object at the desired location of seve'rance, said air-gas mixture being a mixture of the combustible gas and sufiicient air to support its combustion and being capable of providing sufiicient heat upon combustion of the gas to sever said casing.

5. A method of severing casings which comprises filling a portion of the casing immediately below the desired point of severance with a non-combustible material; placing a piece of solid exothermic combustible material having a relatively low kindling temperature immediately above the non-combustible material; suspending a rotatable tubular drill member of harder material than said combustible material in said casing in a manner such that it can be contacted at its end with said combustile material and caused to exert pressure on said combustible material as it is rotated, said drill member being provided with a plurality of holes in said end; rotating said drill member with its end in contact with said combustible material while causing it to effect pressure on the combustible material and substantially simultaneously forcing a combustible gas and a combustion-supporting gas through said holes, whereby said combustible material is ignited by friction to ignite said combustible gas to effect simultaneous burning of the combustible material and the combustible gas to sever said casing by the heat formed, the products of combustion being forced out of the casing between said drill member and the internal wall of said casing.

6. The method of claim 5 in which said combustible material is adapted to be ignited by friction.

7. The method of claim 5 in which said combustible material is a carbonaceous material.

8. A method of severing casings which comprises filling a portion of the casing immediately below the desired point of severance with a non-combustible material; placing a piece of solid exothermic combustible material having a relatively low kindling temperature immediately above the non-combustible material; igniting said combustible material and circulating into the burning area of ignited combustible material a combustible gas and a combustion-supporting medium; whereby the simultaneous burning of said combustible material and said combustible gas produces sufficient heat to sever said casing, and the products of combustion are forced out of the casing by circulatory movement caused by incoming gases.

9. In apparatus adapted to sever casing at a predetermined location in a well bore wherein a combustible heat generating substance is disposed within the casing at the selected area of severance, the combination of a rotary tool suspended in the casing for rotation with its lower end in frictional engagement with the heat generating substance to cause burning thereof, means for conducting under pressure a combustion supporting gas into the burning area and into contact with said heat generating substance, and said gas being circulated through said conducting means into contact with the heat generating substance and out of said casing and being operative in combination with heat developed by friction resulting from rotation of said rotary tool to cause the development of heat suflicient to cause complete burning of said heat generating substance with the resulting severance of the casing.

10. In apparatus to sever casing at a predetermined location in a well bore wherein a combustible heat generating starter substance is disposed at the location of severance, the combination of a hollow rotary tool disposed for rotation at the lower end of a drill pipe in direct frictional contact with said substance, said tool including at least one opening adjacent the area of frictional contact, a combustion supporting gas being circulated down said tool into contact with said substance and out said casing, whereupon the combined flow of said gas through said opening and rotation of said tool are cooperative to cause development of heat sufficient to raise the temperature of the substance above that of combustion thereby to cause burning of the substance and severance of the casing.

11. In apparatus adapted to sever casing at a predetermined location in a well bore wherein a heat generating exothermic substance is positioned at the desired location of severance, the combination of a generally tubular rotary tool connected to the lower end of a drill pipe in direct contact with an exposed portion of the exothermic substance, said tool having a lower extremity formed of heat resistant material frictionally engaging the substance and with openings provided at the extremity of said tool, said tool serving as a conduit for introduction of gas under pressure into contact with said substance, a combustion supporting gaseous circulating medium being directed through said rotary tool under pressure and into contact with said substance and out of said casing, whereby the combined application of said combustion supporting gas and rotation of said tool are cooperative to generate heat in said substance above its temperature of combustion thereby to cause complete burning of the substance and severance of the casing.

12. In apparatus adapted to sever casing at a predetermined location in a well bore wherein a combustible substance is positioned at the point of severance, the combination of an elongate generally tubular rotary tool connected to the lower end of the drill pipe for extension through the casing and having a rounded nose portion to contact the top exposed surface of the combustible substance with openings at the extremity of said nose portion to provide for the ejection of a circulating gaseous medium, said tool serving as a conduit for introduction of said gaseous medium into contact with said substance, a gaseous mixture of a combustible gas and a combustion supporting medium therefor being circulated under pressure down said tool into contact with said substance and out said casing, the introduction of said gaseous medium into contact with said substance being cooperative with rotation of said tool to cause generation of heat sufiicient to ignite said substance and said gaseous mixture thereby to cause complete burning of said substance in the casing, the circulation of said gaseous mixture through said casing being operative to remove the waste material formed in burning said substance and casing.

References Cited in the file of this patent UNITED STATES PATENTS 1,643,726 Ramsey Sept. 27, 1927 2,286,782 Aitchison June 16, 1942 2,436,036 Defenbaugh Feb. 17, 1948 2,500,990 Higginbotham et al Mar. 21, 1950 2,548,463 Blood Apr. 10, 1951 2,680,486 Carpenter June 8, 1954 2,776,816 Jackson Jan. 8, 1957 2,786,660 Alleman Mar. 26, 1957 2,896,914 Ryan r July 28, 1958 2,967,052 Crawford Jan. 3, 1961 FOREIGN PATENTS 472,759 Canada Apr. 10, 1951 

1. A METHOD OF SEVERING A CASING AND THE LIKE IN A WELL BORE COMPRISING THE STEPS OF POSITIONING A CARBONACEOUS MATERIAL IN DIRECT PHYSICAL CONTACT WITH THE DESIRED LOCATION OF SEVERANCE OF THE CASING, BURNING AN EXPOSED PORTION OF THE MATERIAL WHILE DIRECTING AN AIR-GAS MIXTURE AGAINST THE EXPOSED PORTION OF THE MATERIAL TO CAUSE COMPLETE BURNING BOTH OF THE MATERIAL AND THE AIR-GAS MIXTURE, AND CONTINUOUSLY CIRCULATING THE GAS-AIR MIXTURE THROUGH THE CASING TO CAUSE DESTRUCTION OF THE CASING AND SUBSEQUENT REMOVAL OF THE WASTE MATERIAL ACCUMULATED DURING BURNING OF THE SUBSTANCE AND CASING SAID AIR-GAS MIXTURE BEING A MIXTURE OF A COMBUSTIBLE GAS AND SUFFICIENT AIR TO SUPPORT ITS COMBUSTION AND BEING CAPABLE OF PROVIDING 